working principle of capacitive type level transmitter
Answers
Working Principle:
The principle of capacitive level measurement is based on change of capacitance. An insulated electrode acts as one plate of capacitor and the tank wall (or reference electrode in a non-metallic vessel) acts as the other plate. The capacitance depends on the fluid level. An empty tank has a lower capacitance while a filled tank has a higher capacitance.
A simple capacitor consists of two electrode plate separated by a small thickness of an insulator such as solid, liquid, gas, or vacuum. This insulator is also called as dielectric.
Value of C depends on dielectric used, area of the plate and also distance between the plates.
Where:
C = capacitance in picofarads (pF)
E = a constant known as the absolute permittivity of free space
K = relative dielectric constant of the insulating material
A = effective area of the conductors
d = distance between the conductors
This change in capacitance can be measured using AC bridge.